Feet are, without doubt, the unsung heroes of human anatomy. They literally carry us on their backs, through thick and thin, and as a result, feet suffer untold abuse during the course of human activities. Indeed, shoes were likely invented by primitive man to protect their feet from crippling injuries, and thereby to increase the duration and/or the vigor of their daily adventures. Such protection could literally mean the difference between life and death. As human experience progressed, and activities varied, so has our skill, innovation, and objectives with regard to shoe design and construction.
At some point in human history, shoes assumed alternative and/or dual roles as both functional items and objects of aesthetic expression. So thoroughly has this latter interest developed, that some modern shoes have completed a historical circuit. They are highly prized and sought out for their aesthetic qualities, in spite of their tendency to inflict pain and injury upon the user's feet.
For some activities, for example for industrial work and/or athletics, shoes mainly retain functional and injury-prevention purposes, and their construction, including design and materials, are suited primarily for those purposes. Advancements in knowledge and technology (e.g., material science, human anatomy and kinesiology, etc.) have led to the development of innovative shoe designs, construction, and materials, as well as staggering levels of use-based specialization in the same. So much so, that a shoe designed for a particular purpose (e.g., sprinting), can include numerous design, material, and construction variations depending upon such factors as the type of intended running surface, the morphological and kinesthetic characteristics and running style of the individual user, and even the expected weather conditions.
However, the evolution of the design and construction of shoes intended for primarily aesthetic (e.g., fashionable) purposes has followed a divergent and rather stunted path. Once established, aesthetics remains a primary selection criterion by a large segment of consumers, and therefore also the primary design consideration. This is true despite research showing that wearing shoes that dramatically affect posture, foot angle, balance, and other kinesthetic factors, can and does lead to improper anatomical alignment and physiological damage taking a host of forms.
Many (primarily women's) fashion shoes feature an elevated heel portion (e.g., high-heels, pumps, platforms, wedges, etc.), which produces a shoe that can be marginally, substantially, or even extremely inclined along its anterior-posterior axis. Further, many such shoes include relatively insubstantial uppers, designed for appearance and to merely hold their rather rigid sole to the user's foot, rather than to provide lateral stability and/or support to the foot during use. As a consequence of these features, the natural mechanics of the foot are constrained and compromised, and stresses during use are concentrated into relatively few, small portions of a user's foot. Namely, the “ball” of the user's foot, and to a somewhat lesser extent, the user's heel, are primarily affected, as the user's foot is forced into a plantarflexed condition.
A robust secondary market has developed for generically-designed products, each of which are insertable into a wide variety of shoes (e.g., replaceable, cushioned, full-foot shoe insoles, molded rigid orthotics, heel pads, etc.), to enhance comfort and/or provide, for example, orthopedic benefits. However, very few of these products are suitable for use in women's fashion shoes, such as those having an elevated heel and/or relatively open or otherwise minimally-enclosing upper portions. Inserts tend to shift position at the least, and fall out at the worst, all the while negatively affecting the aesthetics of the shoe. Further, shoe inserts tend to consume volume within the foot-receiving and retaining portion of most shoes, altering the fit and comfort of the shoe for the user.
Additionally, so-called ‘gel’ shoe inserts are typically formed of a soft, rubbery (e.g., flexible, resilient, etc.) material that exhibits limited compression when placed under a load. Once the ‘gel’ of the insole is compressed to or near its limit, a foot in contact therewith tends to ‘bottom out’. That is to say, a gel insole which is compressed at or near its limit presents to a user's foot a rigid resistance to further notable foot-cushioning response. Thus, any shoe insert or other similar structure that ‘bottoms out’ under a load applied during normal use provides inadequate protection, and cumulatively does not mitigate the foot-fatiguing forces involved in normal use. Further, the so-called ‘gel’ inserts are uniformly unitary in construction, and exhibit no fluidic response to an applied force.
In certain athletic shoes, for example, gas-filled chambers (e.g., containing air or some other gaseous fluid) are provided within the thickness of a shoe sole, rather than as separate components, to obviate some of the discussed disadvantages. The compressibility of the gases confined within such chambers, combined with the compressibility and elasticity of surrounding, typically polymeric materials, provides cushioning to a user's foot, particularly to mitigate foot-strike forces during athletic activity. Examples of such structures and uses are described in a family of patents to one Swigart, including U.S. Pat. Nos. 6,796,056, 7,073,276, and 7,243,276, (collectively, the Swigart patents).
However, such gas-filled chambers are generally fully-integrated into shoes, rendering them relatively permanently affixed therein. Thus, when such gas-filled chambers are either penetrated, or wear out, or otherwise lose their hermetic properties, they thereafter fail to provide the intended benefits to the user, and are not replaceable. In such cases, the user typically replaces the shoes. More frequent shoe replacement is accepted in the case of athletic and other more aggressive use-type shoes, as it is well known that the materials lose their beneficial properties more quickly under such conditions, rendering the shoes ineffective for their intended purpose.
The above described situation is unlike the conditions under which more aesthetically-oriented shoes are generally used. Aesthetically-oriented shoes tend to remain fully-functional for a longer period of time, as they are typically used under less aggressive conditions, and also are used less frequently. The latter reason is true inasmuch as the typical user owns numerous different sets of aesthetically-oriented shoes, and uses them in alternation with each other, for example to match other articles of clothing or fashion accessories.
Additionally, the prior art, including the Swigart patents, neither expressly nor impliedly apply to fashion and other shoes having a notably elevated heel portion and/or a relatively rigid (e.g., inelastic) sole material and/or structure. Perhaps more particularly, the prior art does not apply to shoes which, unlike most athletic shoes, are generally not intended or utilized in a manner including running, jumping, rapid direction changes (high-lateral sheer forces between the foot and insole), and aggressive foot strikes. Therefore, despite such advancements in athletic shoe design, construction, and materials, the same is not true for women's fashion shoes, which have remained relatively unchanged for decades, if not longer.